A tiny, ancient, African river fish, Cromeria, is another odd sturgeon

Updated March 31, 2023
with new labels for certain bones in Cromeria (Fig 1), which allies it with Acipenser the sturgeon, and especially with its larvae (neotony at play, Fig 3). Recently a larger marine fish, Gonorynchus (Fig 3), also nested with sturgeons.

Cromeria nilotica
(Boulenger 1901; 4.5cm; Figs 1-3) is an extant tiny African naked shellear previously not associated with Gonorynchus and sturgeons. Note the subterminal mouth. The scaleless body lacks a lateral line. The caudal fin extends anteriorly both dorsally and ventrally.

Figure 2. From Gregory 1933, diagram of Cromeria. Colors added here. Note the odd caudal fin extending anteriorly to the dorsal and anal fins.

Figure 3. Two species of Cromeria, the African naked shellear shown several times life size.

Figure 2. Acipenser (sturgeon) larvae compared (not to scale) with an adult Gonorhynchus.

This appears to be a novel hypothesis of interrelationships.
lf not, please provide a citation so I can promote it here.

References
Boulenger GA 1901. Diagnoses of new fishes discovered by Mr. W. L. S. Loat in the Nile. Annals and Magazine of Natural History, Including Zoology, Botany and Geology, Being a Continuation of the ‘Magazine of Botany and Zoology’, and of Louden and Charlesworth’s ‘Magazine of Natural History’, Series 7 8: 444-446.

wiki/Shortnose_sturgeon_Acipenser
wiki/Gonorhynchus – wiki/Gonorynchus_gonorynchus
wiki/Cromeria